The Mystery of the Millionaire

began to protest.
    “Nothing,” Jim repeated emphatically. “Unless you want to count changing back into swimsuits and having another swim before we go home. That’s what I’m going to do.”
    “Hear, hear!” Mart shouted, turning to follow Jim to the boathouse.
    Trixie stood helplessly, watching them go. Honey came over to her friend and put one arm around her shoulders. “I think another swim sounds like a good idea, Trixie,” she said gently.
    “I think it’s a terrible idea, but I can’t think of a better one,” Trixie said miserably. “I don’t understand how everybody can admit they were being spied on and not want to do anything about it.”
    “All Jim really admitted was that someone was watching us, waiting for us to leave so they could go for a swim,” Laura Ramsey corrected her. “Frankly, on a day as hot as this, that kind of trespassing might not be perfectly legal, but it’s certainly understandable.”
    “You’re right,” Di said. “If I didn’t know the owners of this lake, I don’t think I’d let a little thing like trespassing keep me away.”
    Di sounded so earnest that Trixie, in spite of herself, began to giggle. “All right, Di. If even you don’t see anything wrong in trespassing, it must be okay. So I’ll give up on the spies. But,” she said, narrowing her eyes as she watched Mart emerge from the boathouse and run to the lake, “there are other mysteries going on that I’m going to keep an eye on.”
    Trixie made a point of being in the house the next morning when the mail delivery was due.
    As before, Mart tore out the back door when the mail carrier’s truck approached. Trixie watched him through the kitchen window, and her heartbeat quickened when she saw him walking back toward the house with a large package under his arm.
    She ran to the hall closet, opened the door, and began rummaging through the shelves as if looking for something. From this position, with her back turned, she could avoid scaring Mart into hiding his package, while her ears told her where he went with it.
    The ploy worked. Mart walked by quickly and quietly and went up the stairs. Straining her ears, Trixie heard the door to his room close softly.
    She hurriedly restraightened the contents of the closet and closed the door, leaning against it while she pondered her next move. She was convinced that this mysterious parcel was somehow tied to Mart’s strange behavior over the past few weeks, but she wasn’t sure how to go about finding out what was in it. In the Belden household, bedrooms were considered private territory. Barging in unannounced was forbidden. If she knocked, Mart would have plenty of time to hide the package before inviting her in, and he might not even let her come in the room.
    Trixie thought over her options for a moment, then rapped her knuckles against the closet door for luck. “Yesterday Mart agreed that trespassing is all right sometimes. Today I guess I’ll agree to that, too,” she said aloud.
    She marched up the stairs, walked down the hall to Mart’s room, and wrapped her right hand around the doorknob. Then she knocked sharply twice with her left hand, opened the door immediately, and walked in. “Hi!” she said brightly.
    Mart Belden was taken completely by surprise. He scrambled frantically, trying to put the contents of the package back into the box, trying to hide the box under his bed. When he saw that the box was too big to hide, he stopped abruptly, head down, for a moment, then straightened and looked up. “Hi!” he said, sarcastically imitating his sister’s cheerful tone. “To what do I owe the honor of this visit?”
    “Oh, Mart, you know why I’m here. I’m sorry for bursting in like that, I really am. But I’m just dying to know what’s in that package—and why you’ve been acting so funny lately,” Trixie told him sincerely.
    Mart glowered angrily for a moment, then his face relaxed into an expression that looked almost relieved. “Actually, surreptitious behavior is not my forte,” he said. “But, as you will soon see, the arcane events of the recent past have been motivated by necessity.”
    “What’s in the package?” Trixie said through gritted teeth. She thought that Mart had just told her he was going to explain everything, but she didn’t want to suffer through a long-winded explanation first.
    Mart held up one hand in a wait-a-minute gesture. “First,” he said, “voila!” He took a magazine off the top